Counterbalance For A System For Providing Cyclic Motion

ABSTRACT

In one embodiment, a system for providing cyclic motion includes a magnetic drive having an electrically conductive coil defining a bore and a magnetic member movable through the bore. A control provides current to the coil and selectively reverses the direction of the current to move the magnetic member through the bore. In another embodiment, the system includes a counterbalance. The counterbalance includes a biasing member for reacting against a load applied to a support, and a lever arm coupled to the biasing member for varying a preload of the biasing member. In another embodiment, the magnetic drive and the counterbalance may be incorporated into an apparatus for reciprocating a person.

This application is a divisional of U.S. patent application Ser. No.13/107,111, filed May 13, 2011 (pending), which claims priority to U.S.patent application Ser. No. 11/877,364, filed Oct. 23, 2007, (issued asU.S. Pat. No. 7,958,579 on Jun. 14, 2011), which claims the priority ofU.S. Provisional Patent Application Ser. No. 60/862,914, filed Oct. 25,2006 (expired), the disclosures of which are hereby incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present invention relates generally to machinery and mechanisms thatoperate in a cyclical manner, and more particularly to a counterbalancefor devices that facilitate cyclically operating such machinery andmechanisms.

BACKGROUND

Many machines and mechanisms operate in a cyclical manner. For example,rotating machinery such as turbines rotors, and reciprocating mechanismssuch as paint shakers, exhibit cyclical motion. In use, these machinesand mechanisms may be exposed to varying load conditions. However, manycyclically-operated machines and mechanisms are not able to accommodatevarying loads while maintaining desired performance without substantialincreases in power consumed. A need therefore exists for a simple,efficient system for driving cyclical machines and mechanisms, and foraccommodating varying load conditions.

SUMMARY

A magnetic drive in accordance with the one aspect of the presentdisclosure overcomes the foregoing and other shortcomings of the priorsystems for driving cyclical machines and mechanisms. In one embodiment,the magnetic drive includes an electrically conductive coil defining abore and having first and second oppositely disposed ends. A magneticmember is movable from a first position outside the bore and adjacentthe first end of the coil, through the bore to a second position outsidethe bore and adjacent the second end of the coil. The magnetic drivefurther includes a control that provides current to the coil to generatea magnetic field that interacts with the magnetic member. The control isable to reverse the direction of current through the coil and therebyact on the magnetic member as desired.

In another aspect of the present disclosure, a counterbalance mechanismis provided for offsetting a load applied to a supporting structure. Inone embodiment, the counterbalance includes a biasing member that isadapted to be coupled to a load support for reacting against a loadapplied to the load support. The counterbalance further includes a leverarm coupled to the biasing member. The lever arm is selectivelypositionable relative to the biasing member to vary a preload of thebiasing member. The counterbalance may further include a pivot thatcooperates with the lever arm and which is selectively positionablerelative to the lever arm to vary the preload of the biasing member.

In yet another aspect of the present disclosure, an apparatus forreciprocating a person includes a frame and a support platform that isconstrained to move in a substantially vertical direction relative tothe frame. The apparatus includes a counterbalance, as described above,with a biasing member coupled to the support platform and a lever armcoupled to the biasing member and the frame. The lever arm isselectively adjustable to vary a preload applied by the biasing memberon the support platform.

While various embodiments are discussed in detail herein, it will beunderstood that the invention is not limited to these embodiments. Onthe contrary, the invention includes all alternatives, modifications andequivalents as may be included within the spirit and scope of thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention and, together with a general description of the inventiongiven above, and the detailed description given below, serve to explainthe invention in sufficient detail to enable one of ordinary skill inthe art to which the invention pertains to make and use the invention.

FIG. 1 is a perspective view depicting an exemplary apparatus forreciprocating an infant support, with a cover of the housing shown inphantom.

FIG. 2 is perspective view of the interior components of the apparatusof FIG. 1.

FIG. 3A is a left-side elevation view of the apparatus of FIG. 1, withthe support platform depicted in a raised position.

FIG. 3B is a left-side elevation view of the apparatus of FIG. 1, withthe support platform depicted in a vertically centered position.

FIG. 3C is a left-side elevation view of the apparatus of FIG. 1, withthe support platform depicted in a lowered position.

FIGS. 4A-4F are cross-sectional elevation views of a magnetic drive usedwith the apparatus of FIG. 1, depicting various positions of a magneticmember.

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 2.

DETAILED DESCRIPTION

FIG. 1 depicts an exemplary cyclically operated apparatus 10 includingan exemplary magnetic drive 12 and a load off-setting, orcounterbalancing, device 14 in accordance with the principles of thepresent disclosure. In this embodiment, the apparatus 10 is configuredfor reciprocating an infant so as to soothe the infant in a mannersimilar to that described in U.S. Pat. No. 6,966,082, assigned to theassignee of the present invention and hereby incorporated by referencein its entirety. It will be understood, however, that the drive and loadoff-setting devices 12, 14 described herein may alternatively be used invarious other mechanisms, or may be used independently of one another.

Referring to FIGS. 1, 2, and 5, the apparatus 10 includes a frame 16having first and second spaced frame members 18, 20 interconnected bytransverse beam members 22, 24. In the embodiment shown, the framemembers 18, 20 comprise substantially parallel, vertically-extendingsidewalls 26, 28. The frame 16 may include adjustable feet or casters 30to support the frame 16 above a floor surface, and the frame 16, as wellas other components of the apparatus 10 may be enclosed in a housing 32.As shown in FIGS. 3A, 3B, and 3C, housing 32 may comprise a removableupper cover 32 a and a lower base portion 32 b.

The apparatus 10 further includes a pair of spaced, parallel uppercontrol arms 34, 36 and a pair of spaced, parallel lower control arms38, 40 (see FIGS. 3C and 5) disposed between the vertically extendingsidewalls 26, 28 of the frame 16. Respective first ends 34 a, 36 a ofthe upper control arms 34, 36 and first ends 38 a, 40 a of the lowercontrol arms 38, 40 are pivotally coupled to the frame 16 by pinnedconnections 42, 44. The respective second ends 34 b, 36 b of the uppercontrol arms 34, 36 (see FIGS. 3A and 5) and first ends 38 b, 40 b ofthe lower control arms 38, 40 are pivotally coupled to a supportplatform 46 by pinned connections 48, 50, whereby the upper control arms34, 36 and lower control arms 38, 40 are movable with the supportplatform 46 to constrain movement of the support platform 46 in asubstantially vertical direction.

A seat mount 52 may be secured to the support platform 46 to facilitatecoupling an infant support 54 to the support platform 46, whereby theinfant support 54 will be constrained for movement with the supportplatform 46 in a substantially vertical direction. Travel limitingstops, such as a lower limit bumper 56 (FIG. 5) extending downwardlyfrom support platform 46, and an upper limit bumper (not shown) disposedbetween the lower control arms 38, 40 and frame members 18, 20, may beprovided to control the limits of travel of the support platform 46.While the travel stops are shown and described herein as bumpers, itwill be recognized that various other devices and methods may be used tolimit the travel of platform 46. While this embodiment is described asbeing configured to accommodate an infant support 54, it will berecognized that the apparatus may alternatively be used to reciprocate asupport for a range of persons, from youths to adults, in a mannersimilar to that described in co-pending U.S. application Ser. No.11/257,877, assigned to the assignee of the present invention and herebyincorporated by reference in its entirety.

In the embodiment shown, the frame members 18, 20, the upper controlarms 34, 36, lower control arms 38, 40, and support platform 46 areformed from sheet metal that has been stamped or otherwise worked ormachined to form the respective components of the apparatus. It will berecognized, however, that various other methods for forming the framemembers 18, 20, upper control arms 34, 36, lower control arms 38, 40 andsupport platform 46 may alternatively be used. For example, and not aslimitation, the frame members 18, 20, upper control arms 34, 36, lowercontrol arms 38, 40 and support platform 46 may be formed by molding,casting, machining, or various other methods suitable for fabricatingthe respective components.

With continued reference to FIGS. 1 and 2, and referring further to FIG.5, the apparatus 10 may further include a tunable load-offsetting, orcounterbalance, mechanism 14 for accommodating varying loads that may beapplied to the support platform 46. In the embodiment shown, thecounterbalance mechanism 14 comprises a biasing member 60 disposedbetween the support platform 46 and the frame 16. In this embodiment,the biasing member 60 is a spiral torsion spring having a first end 62operatively coupled to the support platform 46, and a second end 64coupled to a spring lever 66 for selectively adjusting the preload, orinitial deflection, of the spiral torsion spring 60 to correspond to agiven load applied to the support platform 46. The spring lever 66comprises an elongate member having a first end 68 pivotally coupled tothe support platform 46, and a second end 70 cantilevered outwardly fromthe support platform 46 in a direction between the upper control arms34, 36, the lower control arms 38, 40, and the vertically extendingsidewalls 26, 28 of the frame 16. The second end 70 of the spring lever66 is biased in a direction toward the lower control arms 38, 40 by thespiral torsion spring 60.

The spiral torsion spring 60 is coupled to the support platform 46 by apair of semi-circular disks 72 that are pivotally coupled to the supportplatform 46 by an arbor 74 around which the spiral torsion spring 60 iswound. With the first end 62 of the spiral torsion spring 60 connectedto the disks 72, an initial, constant preload of the spiral torsionspring 60 may be selectively adjusted by rotating the disks 72 relativeto the support platform 46 and then securing the disks 72 at a desiredangular position relative to the support platform 46. In the embodimentshown, a plurality of apertures 74 spaced radially from the arbor areprovided around the periphery of the disks 72 and the disks are securedto the support platform 46 by inserting a pin (not shown) through atleast one of the apertures 74 and through a corresponding aperture 76formed in the support platform 46.

The counterbalance mechanism 14 further includes an adjustable pivot, orfulcrum 80, that is selectively positionable along the length of thespring lever 66 to thereby vary a preload of the platform withoutchanging the initial deflection of the spiral torsion spring 60. Withthe platform deflection substantially constant for all preloads, thesystem resonant frequency will also remain constant. In the embodimentshown, the fulcrum 80 comprises a roller supported on a shaft 82extending between the vertical walls 26, 28 of the first and secondframe members 18, 20. The shaft 82 is received in corresponding slots84, 86 formed in the vertical walls 26, 28 of the frame members 18, 20whereby the roller 80 may be maneuvered to various positions along thespring lever 66 by moving the shaft 82 along the slots 84, 86. Tofacilitate positioning the shaft 82 and roller 80 at a desired locationalong the slots 84, 86, pinion gears 88 are provided on the shaft 82 andare rotationally fixed to the shaft 82 at respective ends 90 of theshaft 82 that extend outwardly from the vertical walls 26, 28, as shownin FIG. 2. The pinion gears 88 intermesh with corresponding rack gears92 provided on the vertical walls 26, 28 of the frame members 18, 20,whereby the position of the shaft 82 and roller 80 may be selected byturning the shaft 82 to cause the pinion gears 88 to move along the rackgears 92 to a desired location. Knobs 94 may be provided on therespective ends 90 of the shaft 82 to facilitate turning the shaft 82and pinion gears 88.

With the spiral torsion spring 60 connected between the support platform46 and the spring lever 66, and with the spring lever 66 being pivotedabout the arbor 74 of the spiral torsion spring 60, a load applied tothe support platform 46 is supported as a sprung mass by the spiraltorsion spring 60. Moreover, the static vertical position of theplatform 46 and supported load relative to the frame 16 may beselectively adjusted by manipulating the shaft 82 to cause the roller 80to move along the spring lever 66, as described above. The supportplatform 46 and load, together with the spiral torsion spring 60,therefore comprise a spring-mass system that exhibits a particularnatural frequency. The support platform 46 and supported load may thusbe moved upwardly and downwardly, supported on the spiral torsion spring60, while the upper control arms 34, 36 and lower control arms 38, 40constrain the upward and downward movement in a substantially verticaldirection. The natural frequency of the spring-mass system is related tothe static deflection of the supported load upon the spiral torsionspring 60. Accordingly, by adjusting the static vertical height of thesupport platform 46 relative to the frame 16, using the roller 80 andspring lever 66, the apparatus 10 may be adjusted or tuned toaccommodate a range of loads supported on the support platform 46 whilemaintaining the natural frequency of the spring-mass system.Alternatively, the apparatus 10 may be adjusted with a given load totune the spring-mass system to a desired natural frequency.

Referring to FIGS. 2, 5, and 4A-4F, in another aspect, the apparatus 10may include a magnetic drive 12 mounted to the frame 16 and operativelycoupled to the support platform 46 to move the support platform 46upwardly and downwardly in a cyclical fashion. In the embodiment shown,the magnetic drive 12 includes an electric coil 100 comprisingconductive wire wound to define a cylindrical barrel 102 having acentral bore 104 with oppositely disposed first and second ends 106,108. A magnetic member 110 is sized to be received within the bore 104of the electric coil 100 whereby the magnetic member 110 may be movedfrom a first position outside the bore 104 and spaced from the first end106 of the bore 104 (see FIG. 4A), through the bore 104, to a secondposition outside the bore 104 and spaced from the second end 108 of thebore 104 (see FIG. 4E). In the embodiment shown, the magnetic member 110comprises a stack of individual magnets 112, however, it will berecognized that magnetic member 110 may alternatively comprise a single,unitary magnet. In another embodiment, all components of the drive 12,except the magnetic member 110, comprise non-ferrous materials

When electric current is passed through the coil 100, a magnetic fieldis generated that interacts with the magnetic member 110. Depending uponthe direction of current through the coil 100, the magnetic fieldgenerated by the coil 100 may attract the magnetic member 110, therebypulling the magnetic member 110 in a direction into the bore 104, or thegenerated magnetic field may repel the magnetic member 110, effectivelypushing the magnetic member 110 out from the bore 104. When the magneticmember 110 is coupled to a moveable portion of a machine or device, theelectric coil 100 can be selectively operated to impart motion to thedevice. To this end, the drive 12 may include a control 114 (see FIG. 1)operable to selectively provide current to the coil 100 and toselectively change the direction of the current, as needed, to move themagnetic member 110 through the bore 104 and thereby impartcorresponding motion to the device.

The magnetic drive 12 is particularly useful when the motion of thedevice to be moved is cyclical, such as the cyclical reciprocation ofthe apparatus 10 shown and described herein. In the embodiment shown,the magnetic member 110 is supported on a rod 116 extending downwardlyfrom the support platform 46 and is positioned to be received throughthe bore 104 of the electric coil 100 as the support platform 46 isreciprocated in a substantially vertical direction as discussed above.In one embodiment, as the magnetic member 110 moves downwardly with thesupport platform 46 from a raised position (see FIG. 3A) and approachesthe first end 106 of the bore 104 (see FIG. 4A), no current flowsthrough the coil 100 and no magnetic forces cooperate with the magneticfield of the magnetic member 110 to induce or hinder motion of themagnetic member 110. As the lower edge 118 of the magnetic member 110enters the first end 106 bore of the bore 104 (FIG. 4B), current isprovided to the coil 100 in a manner that generates a magnetic fieldthat attracts the magnetic member 110, causing the magnetic member 110to be drawn into the bore 104 through the interaction of the magneticfields of the magnetic member 110 and the coil 100. The coil 100 remainsenergized as the magnetic member 110 moves into the bore 104. Justbefore the lower edge 118 of the magnetic member 110 exits the secondend 108 of the bore 104 (FIG. 4C), the coil 100 is de-energized to allowthe magnetic member 110 to continue moving in a downward directionwithout the influence of any magnetic field from the coil 100.

Just after the lower end 118 of the magnetic member 110 exits the secondend 108 of the bore 104 (FIG. 4D), the coil 100 is energized withcurrent in a direction to generate a repulsing magnetic field in thecoil 100 that pushes the magnetic member 110 further outside of thesecond end 108 of the bore 104. Just as the upper end 120 of themagnetic member 110 exits the second end 108 of the bore 104, the coil100 is again de-energized and the magnetic member 110 is allowed tocontinue moving in a downward direction with no magnetic forces appliedby the coil 100. As the magnetic member 110 continues moving in adownward direction, the spiral torsion spring 60 is deflected by thecorresponding downward movement of the support platform 46 until thespring force created by deflecting the spiral torsion spring 60 balancesand gradually overcomes the downward inertial force of the loadedplatform 46, and the platform 46 begins to move in the oppositedirection, upwardly away from the ground surface. Now, as the upper end120 of the magnetic member 110 approaches the second end 108 of the bore104 (FIG. 4E), no current is flowing through the coil 100 to createmagnetic field lines that cooperate with the magnetic field lines of themagnetic member 110. As the upper end 120 of the magnetic member 110enters the second end 108 of the bore 104 (FIG. 4F), the coil 100 isenergized to generate an attractive magnetic force that interacts withthe magnetic field of the magnetic member 110 to thereby draw themagnetic member 110 into the bore 104. The magnetic member 110 continuesmoving in an upward direction. Just prior to the upper end 120 of themagnetic member 110 exiting the first end 106 of the bore 104, the coil100 is de-energized to permit the magnetic member 110 to move upwardly,unhindered by any magnetic field generated by the coil 100. Just afterthe upper end 120 of the magnetic member 110 exits the first end 106 ofthe bore 104, the coil 100 is energized with current flowing in adirection that generates a repulsive force that interacts with themagnetic field of the magnetic member 110, thereby pushing the magneticmember 110 further outside the first end 106 of the bore 104. Just priorto the lower end 118 of the magnetic member 110 exiting the first end106 of the bore 104, the coil 100 is de-energized so that the magneticfield generated by the coil 100 is ceased. The magnetic member 110continues to move in an upward direction with the support platform 46until the forces acting on the support platform 46 due to inertia,gravity, spiral torsion spring 60, and the load carried by the supportplatform 60 balance out, whereafter the support platform 46 and magneticmember 110 will begin to move downwardly toward the magnetic coil 100.The control 114 continuously cycles current through the magnetic coil100 in the manner described above and the motion described above isrepeated so that the vertical reciprocating motion of the loadedplatform 46 is maintained.

The magnetic drive 12 described above is particularly useful when thedriven system operates at its natural frequency because a minimum amountof force is needed to be generated by the magnetic drive 12 (to overcomefriction losses, for example) whereby the cyclical motion may bemaintained with the minimum force applied by the drive 12. In theembodiment shown, the natural frequency of the loaded support platform46 may be selectively adjusted by manipulating the roller 80 along thespring lever 66. As the support platform 46 moves upwardly anddownwardly in a reciprocating fashion at the system's natural frequencythe magnetic member 110 will be caused to move into and out of the coil100 as described above, whereby the magnetic drive 12 will maintain thesubstantially vertical reciprocating motion.

Energization of the coil 100 can be automatically adjusted by thecontrol 114 to accommodate variations in natural frequency. In theembodiment shown, the magnetic drive 12 includes a sensor 120 (FIGS. 1,2, and 5) that detects the position of the magnetic member 110 relativeto the electric coil 100 and provides signals to the control 114 toenergize and de-energize the electric coil 100 in the manner describedabove. In this embodiment, the sensor 120 comprises an optical positionsensor 122 operatively coupled to the frame 16, and a positionindicating member 124 coupled to the support platform 46 (see FIG. 5).As the support platform 46 is reciprocated in a substantially verticaldirection, the position indicating member 124 is caused to pass by theoptical position sensor 122. When the optical position sensor 122 sensesthe presence of the position indicating member 124, signals are providedto the control 114 and the control 114 responds by energizing andde-energizing the electric coil 100 to operate in the manner describedabove.

The control 114 may also be configured to automatically turn theapparatus on and off, by selectively energizing and de-energizing theelectric coil 100. For example, the control 114 may be configured todiscontinue energization of the electric coil 100 after a predeterminedperiod of continuous operation, or alternatively after a continuousperiod of non-use. The control 114 may also be configured such thatenergization of the electric coil 100 is ceased if no signal is receivedfrom the sensor 120. With such a configuration, the verticalreciprocating motion of the support platform may be stopped simply byholding the platform at a fixed position, either near the uppermostpoint of travel, or the lowermost point of travel, to thereby preventthe sensor 120 from sending a signal to the control 114. In a similarfashion, the control 114 may be configured to automatically energize theelectric coil 100 at the instant the control receives a signal from thesensor 120 after a period of continuous non-use. When the magnetic drive12 is used with a system that is configured to operate at its resonancefrequency, such as the apparatus 10 described above, and the systemfurther includes a control 114 as described above, a minimum amount ofpower is required to maintain operation of the system. Moreover, poweris conserved by the ability of the control 114 to automatically turn thedrive 12 on and off as needed. In an exemplary embodiment, an apparatus10 for reciprocating an infant support 54 may be powered by six D-cellbatteries and may operate continuously for more than approximately 120hours.

While the present invention has been illustrated by the description ofan embodiment thereof, and while the embodiment has been described inconsiderable detail, it is not intended to restrict or in any way limitthe scope of the appended claims to such detail. The various featuresdiscussed herein may be used alone or in any combination. Additionaladvantages and modifications will readily appear to those skilled in theart. The invention in its broader aspects is therefore not limited tothe specific details, representative apparatus and method andillustrative examples shown and described. Accordingly, departures maybe made from such details without departing from the scope or spirit ofthe general inventive concept.

1. A counterbalance, comprising: a biasing member adapted to be coupledto a load support for reacting against a load applied to the loadsupport; and a lever arm operatively coupled to said biasing member andselectively positionable relative to said biasing member to vary apreload of said biasing member.
 2. The counterbalance of claim 1,further comprising a pivot selectively positionable with respect to saidlever arm and cooperating with said lever arm to vary said preload ofsaid biasing member.
 3. The counterbalance of claim 1, wherein saidbiasing member is a spiral torsion spring.
 4. The counterbalance ofclaim 1, wherein said biasing member and said lever arm cooperate tomaintain a constant resonant frequency with respect to the load appliedto the load support.